1. Field of the Invention
This invention relates to a speed control system for a d.c. motor energized by a thyristor armature supply.
2. Description of the Prior Art
In a d.c. motor drives which are energized by a thyristor armature supply, there is a high armature current rate change when the thyristor supply goes through zero current in connection with a current reversal. The high armature current rate change adversely affects the d.c. motor with concomitant increase in maintenance costs. At times this high current rate change has even resulted in drive speed regulator oscillations. As a result of these considerations, the current controller of the speed control system had to be an operational amplifier having proportional integrator (PI) characteristics rather than one having proportional integrator squared (PI).sup.2 characteristics such as described in U.S. Pat. No. 3,983,464 for "Direct Current Motor Speed Control Apparatus" invented by Robert S. Peterson.